1. Field of the Invention
The present invention relates to a grinding swarf collector designed to satisfactorily collect swarf discharged during grinding of an internal surface of piping.
2. Description of the Related Art
An example of a conventional grinding swarf collector is shown in FIG. 7. This device shown in FIG. 7 is a cutter for an inner peripheral surface of a cylindrical structure, the device being disclosed in Japanese Unexamined Patent Publication No. 61-114083. Collection of swarf in this device will be described.
In FIG. 7, J denotes an induction electric furnace, 101 denotes a refractory lining of the induction electric furnace, 102 denotes an induction heating coil embedded in the refractory lining 101, and K denotes an inner peripheral surface cutter concerned with an earlier technology.
The inner peripheral surface cutter K is composed of a cover 110 for covering an upper opening 103 of the induction electric furnace J; a swivel joint 112 fixed onto the cover 110 via a bracket 111; a strut 114 having an upper end fixed to a turning-side member of the swivel joint 112, and having a lower end passing through the cover 110 and extending near a furnace bottom of the induction electric furnace J, and having a C-shaped cross section because of an axial slit 113 formed in a side wall surface thereof; a first motor M1, disposed on an upper surface of the cover 110, for imparting a rotational driving force to the strut 114 via a gear transmission mechanism 115; a screw member 117 disposed inside the strut 114 coaxially with the strut 114, having an upper end fixed to a stationary-side member of the swivel joint 112, and having a lower end borne by a lower end portion of the strut 114 via a bearing 116; a nut member 118 screwed to the screw member 117; an arm member 119 inserted slidably into the slit 113, having a base end portion secured to the nut member 118, and having a front end portion protruding from the strut 114; a gear-like rotary cutting tool 120 attached rotatably to a front end of the arm member 119; and a second motor M2, disposed on the arm member 119, for imparting a rotational driving force to the rotary cutting tool 120 via a gear transmission mechanism 121.
A cutting operation for an inner peripheral surface of a cylindrical structure by the so constituted inner peripheral surface cutter, i.e., a cutting operation for the refractory lining 101 as the inner peripheral surface of the induction electric furnace J, will be described below. In an initial state, the nut member 118 is situated at the uppermost end of the screw member 117.
As shown in FIG. 7, the strut 114 is inserted into the induction electric furnace J. The upper opening 103 of the induction electric furnace J is covered with the cover 110 whose position is adjusted so that the strut 114 is located at the center of the induction electric furnace J. In this state, the second motor M2 is rotated in a predetermined direction. A rotational driving force of the motor M2 is transmitted to the rotary cutting tool 120 via the gear transmission mechanism 121, whereupon the rotary cutting tool 120 begins to make a rotation about its own axis. Furthermore, the first motor M1 is rotated in a predetermined direction. A rotational driving force of the motor M1 is transmitted to the strut 114 via the gear transmission mechanism 115, whereupon the strut 114 rotates. A rotation motion of the strut 114 is transmitted to the nut member 118 via the arm member 119 which is slidable relative to the slit 113. The nut member 118 rotates while being screwed on the screw member 117. Thus, the nut member 118 descends along an axial direction of the screw member 117 integrally with the arm member 119. Hence, the rotary cutting tool 120 rotates on its own axis at the front end of the arm member 119, and also makes a rotation about the strut 114, with the arm member 119 defining a turning radius. Furthermore, the rotary cutting tool 120 descends along an axial direction of the strut 114. Thus, the rotary cutting tool 120 descends, while making a spiral movement, along the inner peripheral surface of the induction electric furnace J to cut the entire inner peripheral surface of the refractory lining 101 of the induction electric furnace J, where an erosion or the like has occurred, to a desired depth. A large amount of dust or the like, which occurs during this process, is prevented from scattering to the outside of the induction electric furnace J, since the upper opening 103 of the induction electric furnace J is covered with the cover 110.
Besides, the inner peripheral surface cutter K for a cylindrical structure related to the earlier invention is constituted as follows: An opening 130 is formed at a lower end of the strut 114. Piping 131 leading to an external dust collector is connected to the stationary-side member of the swivel joint 112 to make the strut 114 serve as an intake pipe 114'. Further, an opening 132 is formed in the cover 110, and piping 133 leading to the above dust collector is connected to this opening 132 as well. Under the action of the intake pipe 114' and the pipings 131, 133, large amounts of swarf and dust, which have occurred in the induction electric furnace J during the cutting operation for the refractory lining 101, are sucked and discharged to the outside, and treated by the dust collector, etc.
According to the conventional swarf collection technique described above, swarf falling by the action of gravity is sucked and collected. If a cylinder to the processed is placed in a horizontal position or at an angle close to the horizontal, swarf does not reach suction ports, and cannot be collected. The device according to the earlier invention, moreover, is directed at processing a large structure with an internal diameter of 5 meters or more, such as an inner wall of an electric furnace. Thus, it has been unable to collect swarf in a bottlenecked portion with a piping internal diameter of about 10 cm.